1. Field of the Invention
This invention is related to wellbore operations and, in certain particular aspects, to systems for providing primary barriers in wellbores and temperature compensation for fluid actuated apparatuses.
2. Description of Related Art
Often in a wellbore or within a tubular member in a wellbore it is desirable to have an effective sealing barrier between an upper portion of the wellbore or tubular and a lower portion thereof. A variety of prior art bridge plugs and cement systems provide barriers in wellbores and tubulars. Such a barrier is, preferably, impervious to fluids in the wellbore or tubular; unaffected by temperatures encountered in the wellbore or tubular; and strong enough and sufficiently securely emplaced to withstand forces thereon, e.g. by a dropped tool or piece of equipment.
Prior art fluid set bridge plugs can burst or deform when subjected to unusually high temperatures and may deform or shrink when subjected to unusually low temperatures - either of which temperature changes can impair their proper functioning.
FIG. 1 shows a typical prior art cement system in which cement C has been emplaced through a bull plug and hardened above and below an inflated packer P. The cement below the packer has sealed off a lower set of perforations R and has sealed off the interior of a casing S below an upper set of perforations T so that fluids from a formation F may flow to a production string G and then to surface collection equipment. Installation of a system as shown in FIG. 1 is a complex, expensive, time-consuming job.
Typical inflatable packers and other wellbore tools and apparatuses operated by fluids can be adversely affected when the temperature of actuating fluid changes or when the temperature of fluids contacting the apparatus changes. Also various fluid actuated anchor devices can be adversely affected by such temperature changes.
There has long been a need for an effective and efficient wellbore barrier that is not adversely affected by temperature changes within the wellbore or within a tubular member within which the barrier is emplaced. There has long been a need for such a barrier that serves as a primary barrier which is so securely emplaced that certain forces encountered in a wellbore are insufficient to dislodge, penetrate, or move the barrier. There has long been a need for temperature-compensated apparatus for wellbore operations which include a temperature compensating system so that temperature changes encountered in a wellbore do not adversely affect operation of the apparatuses.